21. Pinball didn't used to have flippers. They were added purely to turn it from a game of chance to...

...a game of skill. "Games of skill" are viewed differently in legal situations such as this.

Very interesting documentary on pinball viewable here on Hulu. The first portion of the documentary covers the legality of pinball in America with all kinds of crazy-awesome facts about pinball. For instance, pinball was outlawed in most major American cities from the 1940's to the mid 1970's.